Supporting device for coated abrasive products



Dec. 23, 1958 W. K. SEWARD SUPPORTING DEVICE FOR COATED ABRASIVE PRODUCTS Filed June 1, 1956 I. A7? I Zda We 2 Sheets-Sheet 1 IN V EN TOR.

. Seward a o/"Hey Dec. 23, 1958 w. K. SEWARD 2,865,144

SUiPORTING DEVICE FOR COATED ABRASIVE PRODUCTS Filed June l, 1956 2 Sheets-Sheet 2 IN VEN TOR.

warren ff: Sea/cum? Q'ZZOWNQQ "face or periphery of the contact wheel.

United States Patent-O SUPPORTING DEVICE FOR COATED ABRASIVE PRODUCTS Warren K. Seward, Kenmore, N. Y., assignor to The Carborundum Company,vNiagara Falls, N. Y., a corporatlon of Delaware Application June 1, 1956, Serial No. 588,759

6 Claims. c1. 51-141 which the abrasive band or belt rotates and which also serves to back up the abrasive band or belt atits area or line of contact with the workpiece being abraded.

The present invention will be described herein primarily as it is adapted and applied to contact wheels and rolls. It is to be clearly understood that it is not to be restricted to wheels and rolls since with appropriate modifications it is applicable and can be similarly embodied in supporting or back-up devices of other types such as supporting platens or belts 'used in backing up coated abrasive belts as they are used in conjunction with one or more idlers or pulleys with or without platen supports.

A specific example of the manner of using coated abrasive belts is the technique known as backstand idler belt grinding. It is common practice under such technique to replace the grinding wheel or a headed set-up wheel used on a floor stand lathe spindle with a socalled contact wheel or roll together with an idler pulley, a tensioning apparatus for moving the idler pulley toward or away from the contact wheel to adjust for minor variations in abrasive belt lengths and to maintain desired belt tension, and a mechanism for'tilting the idler pulley to make the belt track properly. The abrasive belt runs over the contact wheel, which usually serves as the drive pulley, and also over the idler pulley. There may be two or more idler pulleys, as desired, although only one would require tensioning means and belt-tracking apparatus.

During the early stages of using abrasive coated belts in backstand grinding operations a conventional bufi'ing wheel or uncoated set-up wheel was employed as the contact wheel. Subsequently various contact wheels of textile and rubber construction embodying many of the ideas and principles of design commonly found in buffing wheels and set-up wheels were developed which promoted better balance and longer contact wheel life. Although the various improvements in the design of rubber and textile wheels thus resulting achieved a satisfactory degree of balance in contact wheels it was noted that, regardless of the particular type of wheel design, the abrasive belts used therewith rapidly became dull and glazed. Since this was considered to be caused by the continuity or smoothness of the wheel face this smoothness was avoided by cutting channels across the 1 though the resulting wheels tended to improve the performance of the abrasivebelts used therewith the wheels mechanical application.

7 2,855,144 Patented Dec. 23, 1958 "ice typical siren due to the trapping of air. This objectionable feature'became more pronounced as the axial width of the 'wheel increased. The channels in the wheel face were subsequently changed in position to eliminate noise by placing the channels in a diagonal direction in respect of the axis of the wheel.

It has since been established that a serrated type of contact wheel gives betterresults on most grinding applications than do other types of contact wheel or roll. These better results include a faster rate of cut, longer abrasive belt life, cooler cut, a more uniform finish, shorter machine down time because of longer abrasive .life, and less operator fatigue because the action of the contact wheel performs a large part of the work.

However, in some applications serrated contact wheels are found objectionable because they produce an unduly severe flexing action on the abrasive belt which frequently results in premature bond failure and consequently shortens the life of the abrasive belt used in conjunction with the contact wheel. There has further been a definite. need for a better contact wheel or roll, particularly for applications where the work is extremely rough or ragged, such as forgings and castings and is presented to the belt either by hand operation or In many such applications it is essential to a uniform and constant high cutting rate to have a relatively narrow land and a correspondingly The use of a serrated contact presents the disadvantage that when the operator inadvertently applies the workpiece to the abrasive belt too quickly the belt is frequently punctured or ripped by reason of the sudden projection of the workpiece against the belt at a point between lands Where it. is unsupported by the contact wheel peripheral surface. Even in cases I where a puncture does not result there is the frequent The first chanwere highly objectionable because they acted like a setting up of a detrimental repetitive pattern of the contact wheel serrations on the abrasive belt, thereby greatly shortening the useful life of the abrasive belt.

The described invention can also be used successfully on conventional grinding and polishing operations using abrasive belts in conjunction with relatively'soft rubber contact wheels and rolls.

It is an object of the present invention to provide contact wheels or rolls or other supporting devices of improved design which will provide increased life in the abrasive coated belts used therewith.

It is a further object to provide contact wheels, rolls or other devices of improved design which will prevent the premature dulling and glazing of abrasive belts.

It is a further object to provide an improved contact device such as a wheel which will promote greater efficiency in performance of abrasive coated belts and bands used therewith.

It is a still further object to provide a contact device of improved design offering many of the advantages of a grooved or serrated contact device without its attendant disadvantages.

Other objects and advantages accruing from the present invention will become apparent as the description proceeds.

In order that the invention may be more fully understood, reference is made to the various figures of the drawing which depict various illustrative embodiments and phases of the present invention and in which,

Figure l is a schematic side elevation of a contact wheel made in accordance with and embodying features andprinciples of the present invention;

Figure 2 is a frontal elevation of the contact wheel shown in Figure 1;

Figure 3 is a fragmentary side elevation, partially in 3 section, showing schematically in further detail the wheel of Figures 1 and 2;

Figure 4 is a fragmentary side elevation, partially in section, similar to that of Figure 3, showing a modification of the present invention;

Figure 5 is a fragmentary frontal view of the wheel shown in Figure 4;

Figures 6 and 8 are fragmentary side elevations, partially in section, similar to the view shown in Figure 3, of additional modifications of the present invention; and

Figures 7 and 9 are fragmentary front elevations of the wheels shown in Figures 6 and 8, respectively.

Basically, the contact wheel or roll of the present invention comprises a structurally rigid hub portion with arbor hole adapted for mounting upon a suitable shaft or spindle, the hub having a peripheral web and flange usually integral with the hub and composed of metal or other suitable material such as aluminum or steel or plastic, which is in turn integral with, or to which is bonded or mechanically fastened, an annular rim of hard material, such as ebonite or hard rubber, steel or cast iron, heat-hardened resin or plastic compositions, hardened fiber compositions or the like. Obviously, a fully equivalent structural device from the standpoint of the present invention can be provided in which the annular rim embodying the design features of the present invention, with or without its immediately supporting annulus, is constructed separately and designed for attachment to a separately constructed hub and flange portion. The annular rim of hard rubber or other material is serrated on its periphery so that the resulting peripheral face of the wheel comprises a series of lands and grooves about the entire circumference of the wheel. The hardness of this rim member for most operations falls within the range of 30-100 on a Shore durometer D scale. The grooves in the rim are filled with a softer material so that the resulting wheel face is smooth and concentric and is composed of materials of two or more densities or hardnesses. The structural details of the mounting or securing of the rim upon the supporting flange are not a critical part of the present invention and will therefore not be further discussed herein.

The same features can be obtained by casting or machin- 'ing in wheels in which the cylindrical section or rim is made of metal such as aluminum or steel. Although contact devices embodying the present design features offer the maximum benefits and advantages in those applications requiring a relatively narrow, hard land or rib such as one composed of steel, iron or hard rubber or ebonite separated by wide grooves filled with softer material, the present structural features can also be applied with similar advantages to Wheels in which the rim is composed of lands or ribs of relatively soft rubber in the Shore durometer hardness range of 10-90 on the A scale with the intervening grooves of the serrated rim filled with a material of still lower hardness or density such as very soft rubber or sponge rubber.

Highly satisfactory results have been obtained with a contact wheel in which the hub, web and flange elements are integrally formed of aluminum with a rim mounted thereon formed of a vulcanized rubber composition of high Shore durometer hardness such as ebonite or hard rubber. Where metal is employed to form the entire wheel including the rim exclusive of the filling in the grooves, it can be cast, molded, forged or made by any other method as long as the peripheral face of the wheel is provided with a serrated surface with the grooves of the serrated surface substantially filled with a material softer than the material of the rim member.

The softer material used to fill the grooves in the rim can be attached by means of cement, vulcanization, a chemical bond, or a mechanical bond such as by dovetailing. The shape of the serrations cut in the rim of harder material can be square, rectangular, U-shaped,

triangular, scalloped, buttressed thread-shaped, or any combination of such designs. In serrating, the ratio of land to groove area can range from a wheel in which the ratio of land area to groove area is 12 to a ratio of land to groove area of 1:20. However, the benefits derived from contact Wheels embodying the principles of the present invention are greatest in wheels with relatively narrow lands separated by relatively wide groove areas.

Although the invention is described primarily and specifically as it pertains to contact wheels constructed of such a metal hub and rubber composition rim, the subject Wheels of the present improved design can be similarly fabricated with a base or rim of steel, cast iron, textiles, or any other suitable material having the proper characteristics of balance, durability and concentricity under normal operating conditions.

An additional design feature which can be optionally embodied in wheels of the afore-described type in which the rim is serrated and the grooves of the serrated surface filled with a soft material is the provision of a narrow groove or slot along the side edge of the groove adjacent the adjoining land or rib. This feature permits slightly greater deflection of the soft filling material of the groove in use and permits taking full advantage of the harder lands by means of their effect of interrupted cutting action with a minimum danger of puncturing the abrasive belt because of large voids or empty grooves between adjacent hard lands.

Another manner of accomplishing the same objective is the slight recessing of the filling within the grooves so that the outer peripheral surface of the filling material is at least in part below the surface of the land.

A still further modified form of the present invention is a contact wheel in which the grooves of the serrated surface are filled with materials of two or more different densities. For example, the first groove is filled with material having a selected density or hardness softer than the material of the rim and the next groove filled with another material of density different from the filling ma- 7 terial in the first groove and alternate grooves about the circumference of the wheel being filled with the filling materials of the two selected densities.

Referring further to Figures 1, 2, and 3 of the drawings, which depict a contact wheel embodying features of the present invention, the wheel shown consists of a cast aluminum hub 11 provided with a central arbor hole 12 for mounting upon a suitable driving shaft or spindle. The hub 11 is provided with an integral web portion 13 and an axially extending flange 14 which is also integral with the hub 11 and web 13. Mounted and bonded to the periphery of the flange 14 is a rim 15 of substantial thickness composed of hard rubber or ebonite and provided with a serrated peripheral surface 16. The hard rubber lands or ribs 18 of the serrated surface are separated by grooves 20 which are filled with a soft rubber composition 19 having a Shore durometer hardness substantially lower than the Shore durometer hardness of the rim 15 and lands 18 thereof. The individual lands and grooves of the serrated surface are disposed diagonally transversely at an angle 0-85", but usually from 60 to 45, as e. g. 45 to the axial direction of the wheel. The contacting surface of the completed wheel structure is substantially smooth and continuous and is composed of alternating zones of hard material extending transversely diagonally across the contacting face of the wheel structure in the form of a plurality of narrow strips separated by relatively wide zones of softer material.

Figures 4 and 5 show a modified form of wheel structure similar to that shown in Figures 1-3 with the added feature that the filling material 21 contained in the grooves 20 is slotted to a depth approximately one-half the total depth of the groove at a point alongside the adjoining land and extending the entire length of the groove from one side of the wheel to the opposing side. The provision of slots in the filling material in this manner serves to impart a greater degree of yieldability to the filling material during the use of the wheel when the workpiece forces the abrasive belt against the filling material. This added yieldability is obtained without any appreciable sacrifice to the overall support which the filling material in the groove provides for the abrasive belt during use.

Figures 6 and 7 show another modification of the present invention in which a soft rubber composition 24 is used as a filling in one-half of the grooves of the wheel and soft rubber composition 25 having a density different from the density of composition 24 is used as the filling material for the remainder of the grooves of the serrated surface, the grooves filled with material 24 alternating with the grooves filled with material 25.

Figures 8 and 9 depict a still further modification of the present invention in which the filling material 27 does not completely fill the grooves 20 of the serrated surface but is slightly recessed to provide a small depression 28 between the ribs which extend above the peripheral surface of the soft filling material. A wheel of this specific construction offers the same operating advantages provided for by the embodiment shown in Figures 4 and wherein the filling material in the grooves is notched or slotted slightly along one side of each groove.

Where hard rubber or ebonite compositions have been specified as the material for the serrated rim, including the lands or ribs of the rim, or where soft rubber or sponge rubber is specified as the filling material within the grooves of the serrated surface of the rim in the herein-described contact devices it is intended to not only include natural hard rubber or natural soft rubber but to also include the various synthetic rubber-base or elastomeric compositions together with the appropriate vulcanizers, plasticizers, fillers and/ or other compounding ingredients, such as the butadiene-styrene copolymers, butadiene-acrylic nitrile copolymers, polyurethane, polychloroprene and the like. Other materials of suitable hardness can be used as the rim composition such as various thermosetting or thermoplastic polymeric substances suitably compounded with or without fibrous, mineral or other filler materials to provide the desired degree of hardness or compressibility to serve as the rim structure or groove filling.

Having described the invention, it isdesired to claim:

1. A contact wheel comprising a hub and a rim, said rim having a transversely serrated peripheral surface comprising a series of transverse lands and separating grooves disposed about the entire periphery of the wheel, said rim being composed of a non-abrasive rigid material with the grooves thereof substantially filled with a resilient solid material softer than the material of the lands, whereby the lands and filling form a substantially cylindrical surface.

2. A contact wheel comprising a hub and a rim, said rim having a transversely serrated peripheral surface comprising a series of transverse lands and separating grooves disposed about the entire periphery of the wheel, said rim being composed of ebonite with the grooves thereof substantially filled with soft rubber.

3. A contact wheel according to claim 2 in which said rim is composed of ebonite and the grooves are filled with porous rubber.

4. A contact wheel comprising a hub and a rim, said rim having a transversely serrated peripheral surface comprising a series of transverse lands and separating grooves disposed about the entire periphery of the wheel, said grooves containing a slightly recessed filling of a resilient solid material having a Shore durometer hardness less than the Shore durometer hardness of the material of said lands, the filling material being permanently bonded to the grooved portions of said rim.

5. A contact wheel comprising a hub and a rim, said rim having a transversely serrated peripheral surface comprising a series of transverse lands and separating grooves disposed about the entire periphery of the wheel, said grooves containing a filling of a resilient solid material having a Shore durometer hardness less than the Shore durometer hardness of the material of said lands, the filling material in each groove being slotted at one side adjacent the adjoining land and being permanently bonded to the grooved portions of said rim.

6. A contact device for abrasive belts, said device comprising a rigid non-abrasive member having transverse slots therein said slots being filled with a solid resilient material, the surfaces of which constitute a continuation of the general outer contacting surface of the rigid member.

References Cited in the file of this patent UNITED STATES PATENTS Re. 24,152 Cosmos May 15, 1956 1,094,361 Blevney Apr. 21, 1914 1,507,836 King Sept. 9, 1924 2,725,691 Sommer et al. Dec. 6, 1955 FOREIGN PATENTS 507,718 Belgium Dec. 31, 1951 

